Portable thermoelectric unit to adjust body&#39;s microclimate

ABSTRACT

A portable thermoelectric unit has a face towards the user&#39;s body. The unit includes at least one flexible layer containing a non-woven fabric or a fabric and/or a polymeric membrane facing the body; a casing having a thermally active area and fixed to a distal face of the layer opposite the face so that the area is in thermal exchange with the layer towards the body; a thermoelectric heat pump device housed in the casing and configured to generate or absorb heat through the area and the layer; a fan housed in the casing and next to the device; a channel in the casing next to the device to receive an air flow generated by the fan in heat exchange with the device and to guide the air flow towards a distal opening from the fan; and a heat exchanger connected to the device on the opposite side of the area to receive the air flow towards the channel.

FIELD OF INVENTION

The present invention refers to a thermoelectric portable unit to increase the comfort of a user, according to a non-limiting example, in clothing to withstand high temperatures, such as a fire retardant suit for an automobile driver.

STATE OF THE ART

A user can be exposed to extreme climatic conditions and the need is felt to provide a portable aid that allows to reduce the impact of these conditions both for heating and for cooling the user according to the situation. It is known to provide heating devices, but the possibilities of providing cooling are less common.

US-2001/0007952 describes a garment provided with a thermoelectric module having a first and a second heat exchange face both exposed to a relative forced air flow within the same environment, delimited by an internal lining on one side and one outer layer of the garment on the other. In this configuration, during operation, the two heat exchange faces initially assume different temperatures for the purpose of heat exchange with the person wearing the garment. However, after a relatively short transient, these faces both go to an intermediate temperature, thus ceasing to define a temperature regulation action for the person wearing the garment.

SCOPES AND SUMMARY OF THE INVENTION

The scope of the present invention is to provide a portable thermoelectric unit for regulating over time the temperature perceived by the user and is, at the same time, efficient and compact.

The scope of the present invention is achieved by a portable thermoelectric unit having a face towards the body comprising:

-   -   at least one flexible layer comprising a non-woven fabric or         fabric and/or a polymeric membrane facing the body;     -   a casing having a thermally active area and fixed to a distal         face of the layer opposite the face towards the body so that the         thermally active area is in heat exchange with the layer;     -   a thermoelectric heat pump device housed in the casing and         configured to generate or absorb heat through the thermally         active area and the layer;     -   a fan housed in the casing and on a side of the thermoelectric         device;     -   a channel in the casing on a side of the thermoelectric device         to receive through the thermoelectric device an air flow         generated by the fan and guide said flow towards an opening         distal from the fan;     -   a heat exchanger connected to the thermoelectric device on the         opposite side of the thermally active area so as to receive the         air flow generated by the fan towards the channel, wherein,         between the thermally active area and the heat exchanger, only         the heat exchanger is exposed to the air flow.

This unit is compact, light and offers effective heat exchange with the user towards the thermally active area. In fact, only the heat exchanger is exposed to the air flow in order to increase the thermal gradient of the thermoelectric device with the thermally active area. In addition, efficiency is increased because the fan and the distal opening are spaced from each other via the channel that leads the air from the heat sink to the distal opening. In this way the air exhausted through the distal opening is not re-aspirated by the fan. In this regard, the duct has a minimum length of at least 3 times the diameter of a fan impeller.

According to a preferred embodiment, the thermoelectric device adheres to the thermally active area or the casing defines a window facing a face of the thermoelectric device opposed to the exchanger. In both cases, the air flow is adducted through the exchanger and is inside the casing while the opposite side of the thermoelectric device exchanges heat outside the casing. This increases the thermal gradient achieved by the unit for the benefit of a greater control of the heat exchange with the body.

According to a preferred embodiment, the casing is substantially flattened and oblong so as to keep the fan, the heat exchanger and the air flow side by side and substantially aligned along its axis, and also allows to convey in an orthogonal direction to its axis the incoming and outgoing air flows.

The flattened and oblong shape is compact and allows the unit to be mountable, for example in clothing filling.

According to a preferred embodiment, the casing is soft and elastically hand deformable, for example manufactured by including a polymeric material based on silicone or thermoplastic polyurethane. Preferably the polymeric material comprises a polyol and an isocyanate to obtain the best compromise between flexibility and flame resistance. In particular, flexibility can be further regulated through a ‘chain extender’, i.e. an add-on to polyol and isocyanate.

Furthermore, the casing defines precise shapes, e.g. the duct, the housing for the fan and the thermoelectric device, at least in an undeformed condition and allows to absorb shocks or take the position of the body maintaining high user comfort.

According to a preferred embodiment, the channel comprises one or more spacers arranged in a transverse position of the channel to avoid or limit collapses of the channel in case of applied loads having a component parallel to a height of the cross section of the channel.

According to a preferred embodiment, the casing defines an intake opening for feeding the fan, the intake opening and the distal opening being both arranged on a face of the housing opposite to that of the thermally active area.

Being designed for interaction with a user on the part of the thermally active area, the most favorable area for the exchange of air flows is the one opposite to the face facing the body.

According to a preferred embodiment of the present invention, a garment comprises the thermoelectric unit as described in the previous paragraphs, in which the casing is arranged in a multilayer fabric (so-called “compound”) or in a filling delimited towards the outside from a textile layer. Preferably, the garment is a fire retardant suit, for example a suit for a race car driver, and the thermoelectric device is configured to absorb heat through the thermally active surface.

BRIEF DESCRIPTION OF THE FIGURES

The present invention will be described below by means of some preferred embodiments, given as a non-limiting example, with reference to the attached drawings. These drawings illustrate different aspects and examples of the present invention and, where appropriate, structures, components, materials and/or similar elements in different figures are indicated by similar reference numbers.

In particular:

FIG. 1 refers to a schematic longitudinal section of a thermoelectric unit according to the present invention; is

FIG. 2 refers to an exploded perspective view of an embodiment of the unit schematically shown in FIG. 1;

FIG. 3 is a perspective view from below of the thermoelectric unit of FIG. 2;

FIG. 4 is a graph illustrating experimental results of the temperature trend of the thermally active area during a cycle of increase and decrease of the electrical power supply; and

FIG. 5 is a graph showing experimental results of stabilization over time of the temperature at constant voltage supply of the thermoelectric device.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1,1 indicates as a whole a thermoelectric unit comprising a flexible layer 2 for example comprising a fabric adapted in use to face a user and, preferably, in contact with the user's skin, an casing 3 elastically deformable to increase comfort while the user is moving and carrying the thermoelectric unit 1, a thermoelectric device 4 inside casing 3 to absorb or give heat to the user, a fan 5 inside casing 3 to generate an air flow in heat exchange with thermoelectric device 4 and inside casing 3, and a channel 6 located downstream of thermoelectric device 4 to adduct the air flow in a zone distal to that of intake fan 5.

Furthermore, unit 1 comprises a heat sink 7 inside casing 3 and arranged between fan 5 and channel 6 to receive the air flow and increase the efficiency of the thermoelectric device 4. Heat sink 7 operates when the thermoelectric device cools the body; more generally, an air-solid heat exchanger, for example with fins, is associated with the thermoelectric device.

In particular, thermoelectric device 4 is a solid state heat pump, e.g. a Peltier cell, and is powered by direct current and, in a first polarity, a face 8 of thermoelectric device 4 facing the user absorbs heat and produces a cooling sensation; and in an opposite polarity, face 8 provides heat and produces a feeling of warming for the user. Consequently, a face of thermoelectric device 4 opposed to face 8 and arranged in heat exchange with heat sink 7 raises its temperature with respect to face 8 when the power supply is according to the first polarity; and such a face with heat exchanger 7 has a lower temperature than that of face 8 when the polarity is reversed.

Fan 5 is preferably a radial fan and generates an air flow having a predefined rectilinear direction that reaches channel 6 through heat sink 7 so as to increase the efficiency of thermoelectric device 4. Channel 6 extends in a substantially parallel direction to that of the air flow and opens into a discharge opening 9 distal from fan 5, preferably arranged at one end of casing 3.

Casing 3 is connected to flexible layer 2 according to different methods applied in the clothing manufacturing industry, for example, both disconnectable through e.g. velcro, snap buttons, laces or the like, and permanently, for example through adhesives, welds between polymeric materials or the like. In the diagram of FIG. 1, face 8 is facing the user's body the flexible layer 2 also has a face facing the body. A preferred application of the unit of the present invention is the insertion of casing 3 into the filling of a garment and, as illustrated in FIG. 1, this requires unit 1 to be coupled to a fabric or other external flexible layer 10, i.e. opposed to flexible layer 2, and that a face of flexible layer 2 opposed to that towards the body is in contact with the filling.

According to a preferred embodiment of the present invention, in particular when external flexible layer 10 is breathable or is a fabric, the cooling or heating action via face 8 requires an air flow through fan 5 such as to pass through flexible layer external 10 without particular difficulties or impact on the efficiency of thermoelectric device 4.

Flexible layer 2 towards the body can also have a weft and warp spaced apart so as to allow the transmission of heat through face 8 or require a modification in the area superimposed on face 8 to increase the efficiency of heat transmission. For example, the modification involves the application of openings and may include the opening of a window having for example the size of face 8 and, optionally, the application to the window of a fabric with a sufficiently spaced weft and warp or the like.

Face 8 can be completely exposed to flexible layer 2 through e.g. a window open in casing 3 or casing 3 comprises an area in contact with face 8 having openings arranged in a matrix or in another way and shaped in such a way as to allow the heat exchange between face 8 and the user's body.

According to a preferred embodiment of the present invention, both distal opening 9 and an intake opening 11 of fan 5 are either peripheral or opposite to face 8 and to flexible layer 2 so as to face towards a more free area and not occupied by the user's body and, therefore, more efficiently generate the air flow.

According to the embodiment of FIG. 2, fan 5, a central zone of thermoelectric device 4 and a central zone of an intake port of the channel 6 are substantially aligned. Furthermore, channel 6 has a substantially rectilinear shape to distance itself from intake opening 11 so as to give casing 3 an oblong and substantially flattened shape. Both distal opening 9 and intake opening 11 are arranged on the same face of casing 3 opposed to the face 8 (FIG. 3).

Preferably casing 3, for example comprising two half-shells, is manufactured of an elastically hand deformable polymeric material, for example based on silicone or thermoplastic polyurethane. The latter also has a flame-resistant behavior and is suitable for applications within heat-resistant clothing such as a suit for a race car driver. When casing 3 is thus manufactured, it is important to always keep channel 6 clear even when, for example, the user presses against the casing with his whole body against a rigid wall. To counteract this load, one or more spacing projections 12 are arranged in channel 6, elongated in a transverse direction, preferably approximately perpendicular, to face 8.

FIG. 4 illustrates the superimposition of first experimental data (circumferences—dark color) measuring the electrical power supply of the thermoelectric device 4 in the cooling mode as the supply voltage changes in a dynamic increase and decrease cycle; and second experimental data (squares—light color) measuring the difference between the ambient temperature, i.e. 24° C., and the temperature of face 8 as the supply voltage varies according to the same cycle adopted for the power measurement. The graph shows the presence of a zone of maximum cooling efficiency around 5 V of power.

FIG. 5 illustrates experimental results of the temperature of face 8 in the cooling mode of the thermoelectric device 4 at a constant supply voltage over time.

Finally, it is clear that modifications or variations can be made to the portable thermoelectric unit according to the present invention without thereby departing from the scope of protection as defined by the attached claims.

For example, the unit is also applicable within sleeping bags, backs of backpacks, hammocks etc. with or without filling and with the flexible layer facing the body.

It is also possible that the user is an individual or an animal, for example a companion animal.

Based on these numerous applications, it is possible that the flexible layer 2 is not of fabric or non-woven fabric, but a continuous membrane, for example made by molding or laminating, of a polymeric material.

According to the embodiment illustrated in FIGS. 2 and 3, the power supply of the thermoelectric device 4 is external to unit 1 and electrical wires of suitable length electrically connect device 4 to a battery. However, it is possible to provide a rechargeable battery or a supercapacitor on board casing 3.

Further applications in heat-resistant clothing include the use on board of firefighter suits and for personnel working in furnaces for metalworking or for foundry work. 

1: A portable thermoelectric unit having a face towards the body of a user, the unit comprising: at least one flexible layer comprising a non-woven fabric or a fabric and/or a polymeric membrane facing the body; a casing having a thermally active area and fixed to a distal face of the layer opposite the face towards the body so that the thermally active area is in thermal exchange with the layer towards the body; a thermoelectric heat pump device housed in the casing and configured to generate or absorb heat through the thermally active area and the layer; a fan housed in the casing and next to the thermoelectric device; a channel in the casing next to the thermoelectric device to receive a flow of air generated by the fan in heat exchange with the thermoelectric device and to guide the air flow towards a distal opening from the fan; a heat exchanger connected to the thermoelectric device on the opposite side of the thermally active area so as to receive the air flow generated by the fan towards the channel, wherein, between the thermally active area and the heat exchanger, only the heat exchanger is exposed to the air flow. 2: The unit according to claim 1, wherein the thermoelectric device adheres to the thermally active area. 3: The unit according to claim 1, wherein the thermally active area comprises a window facing a face of the thermoelectric device opposed to the heat exchanger. 4: The unit according to claim 1, wherein the casing is substantially flattened and oblong so as to keep the fan, the heat exchanger and an intake of the channel arranged side by side and substantially aligned. 5: The unit according to claim 1, wherein the casing is soft and elastically hand deformable and comprises a polymeric material based on silicone or thermoplastic polyurethane. 6: The unit according to claim 5, wherein the polymeric material comprises an isocyanate and a polyol. 7: The unit according to claim 5, wherein the channel comprises one or more spacing projections arranged in one or more cross sections of the channel to avoid or limit collapses of the channel in case of applied loads on the housing. 8: The unit according to claim 1, wherein the casing defines an intake opening to supply the fan, and the intake opening and the distal opening are arranged on a face of the housing opposite to the thermally active area. 9: A heat-resistant garment, comprising the unit according to claim 1, wherein the at least one flexible layer faces the body of the user and the casing is placed in a filling of the garment. 10: The garment according to claim 9, which is a suit for an automobile driver. 